Painting above, "Olivia's Coop" by Morgan Weistling, demonstrating the armature of a root 2 Dynamic Symmetry rectangle
The Armature of the Rectangle (by Charles Bouleau from "The Painter's Secret Geometry")
The lines that cross within a picture, starting from the corners and from the simple divisions of the sides, have been called in this book the ‘armature’ of the geometrical figure formed in and by the picture. The word can suggest any kind of supporting framework, as for instance the leading of stained-glass windows.
But, falling in with the taste of the painters for musical analogies, I am recalling another sense which the word ‘armature’ has in French, that of a key signature—an idea which illuminates what I have in mind by stressing the impersonal, objective necessity of that inner framework which emerges from the form itself and not from the artist’s choice. He may, in accordance with his idea of art, arrange his picture upon the musical consonances or the golden proportion, or inscribe open or closed curves within the area—in all this he is free; the armature, on the contrary, is given him: he will make more or less use of it, but will never be able to do without it entirely.